where to get play sand

Hello, i just finished building a sand pit for my children and only now realised how expensive is play sand. I need 250kg. B&Q and ToysRus sell 25kg bags for £5. Any other websites or places in Bristol. I don't want to get building sand, since it has got chemicals and the website i found sell either in tonnes or for £90 per 250kg. Any help will be much appreciated. thanks